1. Field of the Invention
This invention relates to a thin flexible metal tube used, for example, at a radiator, and required to be bent in use, subjected to large vibrations under conditions of high temperature and high pressure, and required to have reliable durability.
2Description of the Prior Art
As a conventional technique of such field, for example, a tube connecting an engine 11 and a radiator 12 includes a flexible rubber tube 13 having large flexibility to abosrb great vibrations generated by the engine and transmitted, as shown in FIG. 6.
However, the tube is so thick to satisfy the required pressure tightness, and, therefore, weighty. It must usually be bent in use, so that it is low in productivity and expensive. In addition, since it is made of rubber, it has low heat and weather resistances, so that it is likely to be deteriorated and cracked due to vibrations applied for a long time. Namely, it has the problem of durability.
It is therefore an object of this invention to provide a flexible tube which solves the problems of low productivity, durability and reliability with the conventional flexible tube.
In order to achieve the object, this invention provides a thin flexible metal tube made, for example, of stainless steel, and including a low-corrugation bendable portion and a higher-corrugation straight portion, preferably, having a successive-U- or -.OMEGA.(omega)-like cross section. Provision of the low-corrugation bendable portion in the tube serves to facilitate the bending of the tube with a small force and to increase the rigidity of the bendable portion and to transmit vibrations applied externally to the straight portion. On the other hand, provision of higher-corrugation straight portion of an successive-U- or -.OMEGA.-like cross section serves to absorb vibration transmitted externally via the bendable portion.